Electric impulse generator



Jan. 10, 1950 NEWMAN 2,494,353

ELECTRIC IMPULSE GENERATOR Filed Aug. 9, 1945 P025: 007F417 ram/#415 ill m5: leaner/0N ew/rmz INVENTOR.

HTTOIFA/f) Patented Jan. 10, 1950 uMTE-ns mre's PATENT GEFICEQ ELEGTRIGIMRULSE GENERATOR:-

Edward' Arthur, Newman, Ealing,.London,- Eng;-

land; assignor to EiectrieandjMusical- Industries, Limited, a-British company Application-August 9, 1945, Serial No; 609,89! In (GreatBritain March 8; .1944: Section-1; rumienaw s90;- August-8, 1.946 Batent expires March 8-, 1964= 7 claims. (01. 250 3.6).

constantsof: the coupling impedances. employed-- between the valves of the 1 multievibrator; The control of the impulse-duration and the intervals between thepulses by the. coupling. impedances. imposes an undesirable restriction on r the range of pulse duration andimpulse.intervalsthatcan. lie-obtained and itisaccordinglythe;main.Qbr ject of the. present: invention to provideaniimproved impulse generator. of, the multievibraton type: in. which the control. of. the: impulseduration. and. time intervals.v are. less, dependent, on. the :time constants otithe coupling impedances..,.

According to the invention an impulse generator. isprovided. comprising a. multievibra'tor havinga first valve andasecondvaIVe hichare. so arranged that. when one. of..said valvessissconducting the other valve is non-conductin iazcaw pacity arranged .to.be. chargediroma source of voltage andassociated with the. control electrode of. saidfirst valve,.,an impedance arranged. inthe cathode circuit of. said second valve. and. a uni-' laterallyeconclucting. device associated with. the cathode otsaid secondvalve and. said capacity, the arrangement bein such thatsaid. first valve.

remains non-conducting until the. voltageacrossj saidcapacity rises to apredeterminedvalue. when said. first. valve becomes. conducting, and. said. second valve. becomes. hour-conducting and: the. fall ofv cathode potential. of. the. latter. valve. causes said unilaterally-conducting device..to be:- come conducting and tov discharge saidcapacity.

With. such an arrangement thedurat'ionofthe. impulses, can. be:v adjusted without altering the. timeintervals between. the impulse.s;-. and also. said time. intervals can be, adjusted. withoutQaI: tering. the. duration. of the impulses... Eurthermore, it,is possible, tovarv theduratiOhbIithe.

impulses... and; their. time. intervals over. all very wide ran e; for. examplaitispossible. topmake, the. ratio oi. impulse duratiom to time interval. greater than unity or. to make:- the ratio i oi. the-- order oi /moon.- Eurther, both the impulseduram tion; and. the: time; intervals.- betweem nulses; can; be: larger; for; example; the durationicfi thee itne pulses may be=.as=.large:-as z /zeoieesecondiandthee time intervals may be as large as. 10 seconds's,

In-orderthat thesaid invention may beclearly understood and readily carried into effect, it, will I now be. more: fully: described with reference:

tozthe accompanying; drawing which illustrates: the circuit of an impulse: generator constructed; accordingsto'the preferred-Zform of theinvention.

Asxshownin; the drawing;,the. reference numeral" |:indicates acondenser; one plate of which is earthed and the otherplateofiwhichis con nected to; the control electrode ofiavalvei form ing the firstava'lve of a multi-vibrator and. toone': endiofavariablearesistance 3, the? other: end of i which. is connected; to".- a variable tapping: point:

on: a: resistance. 4;. One end of; theresistance '4 rent'. for: the valve. 2;

positive terminal. of the..- SOLlI'Cf/0f' anode cur-- rent. and via a condenser.- 6; and leak resistance:

1; to the: control electrode of the second ivalve 8 oftthewmultievibratora The anode of the. valve 8. is connected through .a; resistance 9 'to'.the.pos-- itivee terminal: of: the" source of. anodecurrent and a tapping: point omtheresistance 4?. is--:con-

nee-ted: to; a. terminal H which. together; with; the terminal lei connected to. the. negative pole.- ofr the;source'.of. anode current constitute the 3 output: terminals. of; the generator: The; ,cath.

ode-. of the; Valve-=2 isz; connected to the negative.-

polecf: theosource of anode current. through a resistance l'2:whilst,. the. cathodeof .thevalve 8-:

fdrmswitkcach icaithodec-off the" respective .valves a-diode section;. the: auxiliar anode 4 of the valve- 2 being-.1 connected; in: the: manner shown to the platezofi the condenser l which is: connected to: the; cathode; of the: valve 8:: Whilst the auxiliary anodes-of the-valveti is -,-c.onnectedf tothe plate of: I

con-

theecOtldCIlSEi-s l;which is-ccnnected to..the trolielectrodeofrthe; valve 2'.

The operation of the circuitzshownis.as;fo1- lowis': :A'ssllmingzthatthe valve-2 issuddenly randered non:conducting,-. the.- rise in anode: potenti-all of; this: valve. will}. be communicated to the;

control; electrode; of; the valve 3- s0 causing thisvalvestd conduetanddhe;potential oi-its; oath-r -.55-- des will; rises. :Ifhis; rises inzthe. potential ci; thee- 3 cathode of valve 8 causes the diode of valve 8 to become non-conducting, but causes the diode of valve 2 to conduct to hold the cathode potential of valve Zrpositive so holding, valve 2 non-conducting. In this condition the condenser I will be charged from the source of anode current and the rise in potential across the o condenser will be applied to the control electrode of valve 2 and to the anode of the diode section of valve 8. When the charge across the condenser reaches a predeterminedfvalue the valve 2 will be rendered conductin causing the v anode potential of the valve 2 to fall, this fall in potential being communicatedto the valve 8f so as to render the triode section of this valve non-conducting. The cathode potential of the ference between the two frequencies can be caused to control a potential charge so as to provide a control-potential for application to said cathode follower to cause the repetition frequency of the generated impulses to follow said variable freq quency.-

valve 8 also falls with the fall of potential of the control electrode of the valve 8 and to such an extent that the diode section of the valve 8 is rendered conducting and the condenser I is discharged via this diode section mainly at a rate dependent on the values of the resistances I3 and I4. Discharge of the condenser I causes the potential of the cathode of valve 8 to 'fall and also causes the control electrode potential of the valve 2 to fall with the result that the anode potential of the valve 2 rises, such rise in potential being communicated to the control electrode of the valve 8. After a predetermined time the potential of the cathode of the valve 8 falls sufficiently low for the triode section of the valve 8 to be rendered conducting. When the valve 8 is thus rendered conducting the triode section of the valve 2 is rendered non-conducting since the cathode of valve 2 8 as its associated diode which is connected to the cathode of the valve 8 is rendered conducting, whereas since the diode section of the valve 8 is at this stage non-conducting, the control electrode of the valve 2 is disconnected from the cathode of valve 8. The condenser I then recommences to charge and the cycle repeats itself.

The time taken for the condenser I to be charged to a suilicient extent to render the valve 2 conducting controls the time intervals between the generated impulses and can be adjusted by adjusting the resistances 3 and 4. The resistance 3 can be a coarse or range control for this purpose whilst the resistance 4 can be a fine control. time taken for the valve 2 to be rendered nonconducting after having been rendered conducting determines the duration of the generated im-' pulses and this time can be controlled by variation of the resistance I4. The output amplitude of the generated pulse is dependent of the values of the resistances 3 and 4 and also of the condenser I5 and if the resistance I3 is large compared with the resistance l 2 the output amplitude can be made substantially independent of the value of the resistance HI. Since the duration of the impulses and their time intervals are substanwhich is varied or controlled by a control poten-' In such a case the positive end of the-re'-' sistance S-may be connected tothe cathode of-a"- tial.

is maintained at the potential of the cathode of valve The I claim as my invention: l. An impulse generator comprising a first valve and a second valve each having a cathode and a control grid and which are connected to form a multivibrator so that when one of said valves is conducting the other valve is non-conducting, a capacity connected in the input circuit of said first Valve between its control grid and its cathode, means for applying a direct-current charging voltage to said capacity, an impedance connected in the cathode circuit of said first valve, a second impedance connected in the cathode circuit of said second valve, a capacitor coupling the cathode of the first valve to the cathode of the second valve, and a unilaterally-conducting device connected between the cathode of said second valve and the high potential side of said capacity with the anode of said device connected to said high potential side whereby said first valve remains non-conducting until the voltage across said capacity rises to a predetermined value when said first valve becomes conducting and said second valve becomes non-conducting and the fall of cathode potential of the latter valve causes said unilaterally-conducting device to become conducting and to discharge said capacity.

'2. The invention according to claim 1 wherein means is provided for varying the rate of charging .charging of said capacity for changing the pulse duration.

4. An impulse generator comprising a first valve and a second valve each having a cathode and a control grid and which are connected to form a multivibrator so that when one of said valves is conducting the other valve is non-conducting, a capacity connected in the input circuit of said first valve between its control grid and its cathode, means for applying a direct-current charge to said capacity through a resistor, the cathode circuits of each of said valves having a resistor therein to provide a cathode follower action, a unilaterally-conducting device connected between the cathode of said second valve and the high potential side of said capacity whereby said first valve remains non-conducting until the voltage across said capacity rises to a predetermined value when said first valve becomes conducting and said second valve becomes non-conducting and the fall of cathode potential of the latter valve causessaid unilaterally conducting device to become conducting and to discharge said capacity, and a sec- 0ndunilaterally-conducting device and a capacity connected in parallel with each other and each also connected between the cathodes of said valves so that when said second valve is conducting said second unilaterally-conducting device is also conv ducting to maintain the cathode of the first valve at-a potential such that the first valve is non- .conductingv l. r

5. An impulse generator comprising a first valve and a second valve each having a cathode and a control grid and which are connected to form a multivibrator so that when one of said valves is conducting the other valve is non-conductinga capacity connected in the input circuit of said first valve between its control grid and its cathode, means for applying a direct-current charging voltage to said capacity, an impedance connected in the cathode circuit of said second valve,' and a unilaterally-conducting device connected 'between the cathode of said second valve and the high potential side of said capacity whereby said first valve remains non-conducting until the voltage across said capacity rises to a predetermined value when said first valve becomes conducting and said second valve becomes non-conducting and the fall of cathode potential of the latter valve causes said unilaterally-conducting device to become conducting and to discharge said capacity, and wherein the cathodes of said first and second valves are coupled together via a capacity, and a second unilaterally-conducting device is provided which is connected between the cathode of said first valve and the cathode of of said capacity for changing the pulse repetition 7 rate.

7. The invention according to claim 5 wherein means is provided for varying the rate of discharging of said capacity for changing the pulse duration.

EDWARD ARTHUR NEWMAN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,113,011 White Apr. 5, 1938 2,161,948 Bull et a1 June 13, 1939 2,185,363 White Jan. 2, 1940 

